hi there! my question goes: Gas fireplaces burn methane using oxygen from the air. If 4.00L of methane is burned,predict the volume of...

Methane has a molecular formula given by CH4. The reaction
that occurs when it reacts with O2 is CH4 + 2O2 --> CO2 +
2H20.

We can use the Ideal Gas Law, PV= nRT to determine
the volume of oxygen required to burn 4.00L of methane. We assume the variables of
temperature (T) and pressure (P) are the same when the volume of oxygen is being
calculated. So from PV= nRT, we get that V is proportional to n or the volume is
proportional to the moles of gas required.

Now the equation
of the reaction between methane and oxygen, gives us that 2 moles of oxygen are required
for each mole of methane. Also, the volume of the gas required is proportional to the
number of moles. Therefore for the complete combustion of 4.00 L of methane we need
2*4.00 = 8.00 L of oxygen.

The required
volume of oxygen is 8.00L.

Hope this
explanation helped you.